US3489356A - Pulping apparatus - Google Patents

Description

Jan. 13, 1970' w. H. COMES ET AL I 3,489,356

PULPING APPARATUS Filed Sept. 20, 1966 W 2 Sheets-Sheet 1 I N VEN TORS WILLIAM H. COMBS SAM N. CRAIG ELLIS R` WARNER, JR.

ATTORNEYS.

Jan. 13, 1970 w. H. COMES ET AL'. 3,489,356

PULPING APPARATUS Filed Sept. 20, 1965 2 Sheets-Sheet 2 4gb B c l l 38 A *a D 30 4o Fv S- /f/ 1 28 36 j E H IC7/Q 5 Fig. 4

Fl'g. 5

JNVENTORS.

I WlLLlAM H. COMBS SAM N. C Al R G ELUS R. WARNER,JR.

BY @M+-M ATTORNEYS.

United States Patent M PULPING APPARATUS William H. Combs, Wayne, Sam N. Craig, Devon, and

Ellis R. Warner, Jr., West Chester, Pa., assxgnors to Wascon Systems, Incorporated, Hatboro, Pa., a corporation of Pennsylvania Filed Sept. 20, 1966, Ser. No. 580,445

Int. Cl. B02c 7/08, 7/12, 13/28 U.S. Cl. 241--74 16 Claims ABSTRACT 0F THE DISCLOSURE A pulping apparatus is provided, comprising a slurry tank having an impeller mounted at the bottom thereof, for rotation, whereby circular movement of the slurry is eiected. Teeth are provided on the impeller for pulping the slurry solids, and the slurry is discharged fom the tank by being impelled through a screen. Vanes on the impeller cause the circulating slurry to pulsate to eifectively dislodge solid particles which may otherwise tend to lodge in or on the screens.

'I'his invention relates generally to pulping apparatus for the solids in a liquid slurry thereof, and particularly to pulping apparatus of the type wherein the mixture of liquid and solids to be pulped is contained in a tank which is provided with an impeller mounted in the bottom thereof for rotation on a vertical axis, whereby to cause circulatory movement o-f the mixture of liquid and solids, and which is also provided with a screen located in the path of the solids discharged by the impeller and controlling the passage of pulped particles to the outlet from the tank.

An important object of the invention is to provide pulping apparatus of the type aforesaid wherein the impeller has novel and improved structural characteristics which give increased insurance against clogging of the screen.

Another object is to provide such an impeller which effects continuous cleaning of the perforations of the screen by causing the material to pulsate, the pulsing action being effective to dislodge particles of solids tending to lodge in Oron the screen.

Another object is to provide such an impeller with improved cutting teeth for reducing the solids in the liquid slurry thereof to a pulp, and for shedding any incompletely pulped solids tending to dwell thereon.

Other objects of the invention will become apparent when the following description is read with reference to the accompanying drawings, in which:

FIGURE l is a vertical, longitudinal section through apparatus constructed in accordance with the invention;

FIGURE 2 is a section on line II-II in FIGURE l;

FIGURE 3 is an enlarged section on line III-III in FIGURE 2;

FIGURE 4 is a perspective view of a block illustrating how the cutting teeth may be made; and i FIGURE 5 is an enlarged section on line V-V in FIGURE 2, showing one of the cutting teeth, made as indicated in FIGURE 4, affixed to the `upper surface of the impeller plate.

The following description is directed to the specific form of the invention shown in the drawings and is not addressed to the scope of the invention, which may be practiced in a variety of forms.

Apparatus constructed in accordance with the invention comprises a pulping tank provided with a dished bottom 12 which has a large opening 14 centrally thereof. Underlying the opening 14 is a closure, generally designated 16, including a screen 18 depending from the dished bottom 12 and having a plate 20 extending across the lower extremity thereof. A discharge conduit 22 is Patented Jan. 13, 1970 provided for receiving material discharged from the tank lil through the screen 18 and conducting it to a pump (not shown).

Extending upwardly through the conduit 22 and the plate 20 is a shaft 2.4 to the upper extremity of which is aflixed an impeller, generally designated 26. The impeller is provided with a main body in the form of a circular plate 28 disposed centrally within the screen 18.

Mounted upon the upper surface of the plate 28 is a set of four vanes equally spaced circumferentially about the outer marginal area of the plate. Each vane is in the form of an upstanding plate triangular in shape, being provided with long edges 36 and 38 substantially equal in length and a comparatively short edge 40. The long edge 36 is seated upon the upper surface of the plate 28 and secured thereto, as by welding. The vane is disposed with the llong edge 38 leading. Alternate ones of the vanes, generally designated 30, are disposed with their leading ends farther away from the edge of the plate 28 than their `trailing ends, while intervening ones of the vanes, generally designated 32, are disposed with their leading ends closer to the edge of the plate 28 than their trailing ends. In addition to the vanes 38 and 32, the outer marginal area of the plate 28 has distributed thereover a multiplicity of cutting teeth, designated 42. Referring particularly t0 FIGURE 4, a block of metal A, B, C, D, E, F, G, H is shown cut along a diagonal A-G in such a way as to produce two identical cutting teeth 42a and 42h, each tooth being thus provided with a large diamond-shaped surface A, I, G, I. As illustrated in FIGURE 5, the teeth are secured to the upper surface of the plate (as by welding) with the diamond-shaped surface facing downwardly and, typically, the cutting edge A, E (or C, G) leading. Each said tooth 42, along opposite sides of its leading edge A, E, for example, has non-parallel apex-dening opposed surface portions slopped toward each other and which are connected to each other along the leading edge A, E, said surface portions also connecting the leading edge with the upper surface of the impeller, for at least the length of the leading edge, as is clearly indicated in FIGURES 2, 4, and 5.

In the operation of the apparatus, the tank 10 is charged with a mixture of water and solids, for example, waste materials, and the impeller is rotated in the direction indicated by the arrow in FIGURE 2. The solids are cut up into pulp by the cutting action of teeth 42. The vanes are operative to move the materials circumferentially, and as the solids are cut up into pulp, they move outwardly from the center of the impeller and through the perforations in the screen for discharge into the conduit 22. The pair of vanes 30 moves the slurry outwardly from the center of the impeller toward the screen 18, and the vanes 32 move the slurry in the opposite direction. This results in a pulsing wave of material traveling circumferentially about the screen 18, i.e., pressure and suction alternate across the holes in the screen, which etfectively keeps incompletely pulped solids from plugging the holes in the screen. The pumping effort outwardly is induced in part simply by rotation of the impeller plate 28 (without the aid of the teeth or vanes), and this eifort is increased by outwardly pumping vanes 30. The eifect of the vanes is a function of their size and velocity, which is in turn a function of the radial distance from the center and also of the rotational speed of the impeller. An approximate balance must be established between pumping effort outwardly (induced by plate 28 and vanes 30) and pumping effort inwardly (induced by vanes 32), otherwise plugging of the screen will occur.

When strips of unpulped or incompletely pulped solid materials, such as plastics, rags or paper, are caught on the teeth of the impeller, each trails the tooth upon which it is caught and tends to cover the next following tooth.

Thus the surface of the impeller soon is covered with solid materials and the eciency of the apparatus is reduced. Therefore, it is important to note that the leading edges of the pulsing vanes and of the cutting teeth all incline upwardly and rearwardly so that any solid materials tending to lodge thereon are readily shed.

What is claimed is:

1. In apparatus of the character described, the combination comprising a tank, a closure for an opening in the bottom of said tank including an annular screen extending about said opening and through which pulped solids must pass in order to be discharged from said tank, and an impeller including a plate mounted for rotation within said screen, a plurality of circumferentially spaced upstanding impeller vanes on the upper surface of said plate certain of which are oriented for directing the pulped solids outwardly from said plate toward said screen and others of which are oriented for directing the pulped solids inwardly of said plate away from said screen, and means for rotating said impeller whereby to induce waves of pulped solids moving circumferentially of said tank to pulsate with respect to the perforations in said screen thereby to dislodge solid particles tending to dwell there- 2. The combination according to claim 1 wherein the vanes are elongated elements alternate ones of which are disposed with their leading ends farther away from the outer edge of said plate than their trailing ends, and intervening ones of which are disposed with their leading ends closer to the outer edge of said plate than their trailing ends.

3. The combination according to claim 2 wherein each vane is a triangular plate element having two long edges and a comparatively short edge, one of the longer edges of the vane is seated upon the impeller plate, and the vane is disposed with the other of its longer edges leading.

4. The combination according to claim 2 wherein each vane is a triangular plate element, one edge of the vane is seated upon the impeller plate, and the leading edge of the vane is inclined upwardly and rearwardly.

5. The combination according to claim 1 wherein a plurality of teeth are distributed over the upper surface of the impeller plate, said teeth being operative for reducing solids to a pulp, and each tooth consisting of an element having a leading portion inclined upwardly and rearwardly.

6. The combination according to claim S wherein the vanes are elongated elements alternate ones of which are disposed with their leading ends farther away from the outer edge of said plate than their trailing ends, and intervening ones of which are disposed with their leading ends closer to the outer edge of said plate than their trailing ends.

7. The combination according to claim 6 wherein each vane is a triangular plate element, one edge of the vane is seated upon the impeller plate, and the leading edge of the vane is inclined `upwardly and rearwardly.

8. The combination according to claim -wherein the opposite sides of the tooth are coincident respectively with planes intersecting on a line coincident with a leading edge of the tooth and disposed substantially at right angles to each other.

9. The combination according to claim 8 wherein the leading edge of the tooth is disposed at an angle of approximately thirty-five degrees from the vertical.

10. The combination according to claim 8 wherein the leading edge of the tooth is disposed at an angle of approximately thirty-five degrees from the vertical, andA the back of the tooth is coincident with a plane disposed substantially at a right angle to saidleading edge of the tooth.

11. In a pulping tank having a rotatable impeller disposed at the bottom thereof, the impeller comprising a plate mounted for rotation about its central axis, and a plurality of teeth distributed over the upper surface of said plate and operative for reducing solids to a pulp upon rotation of the impeller, each tooth consisting of an element having a leading portion inclined upwardly and rearwardly wherein the opposite sides of the tooth are coincident respectively with planes intersecting on a line coincident with a leading edge of the tooth and disposed substantially at right angles to each other.

12. The combination according to claim 11 wherein the leading edge of the tooth is disposed at an angle of approximately thirty-five degrees from the vertical.

13. The combination according to claim 11 wherein the leading edge of the tooth is disposed at an angle of approximately thirty-five degrees from the vertical, and

the back of the tooth is coincident with a plane disposed substantially at a right angle to said leading edge of the tooth.

14. In a pulping tank having a rotatable impeller disposed at the bottom thereof, the impeller comprising a plate mounted for rotation about its central axis, and a plurality of teeth distributed over the -upper surface of said plate and operative for reducing solids to a pulp upon rotation of the impeller, each tooth consisting of an element having a leading edge portion inclined upwardly and rearwardly, and each said tooth along opposite sides of said leading edge having nonparallel apex-defining opposed surface portions connecting said leading edge and impeller upper surface for the length of said leading edge.

15. The combination according to claim 14, wherein all said plate-mounted teeth are upwardly disposed.

16. An apparatus of the character described, the combination comprising a tank, a closure for an opening in the bottom of said tank including an annular screen extending about said opening and disposed for dening means for facilitating the direct passage of impelled pulped solids therethrough, through which pulped solids must pass in order to be discharged from said tank, and an impeller including a plate mounted for rotation within said screen, a plurality of circumferentially spaced upstanding impeller vanes on the upper surface of said plate certain of lwhich are oriented for directing the pulped solids outwardly from said plate toward said screen and others of which are oriented for directing the pulped solids inwardly of said plate away from said screen, and means for rotating said impeller whereby to induce waves of pulped solids moving circumferentially of said tank to pulsate with respect to the perforations in said screen thereby to dislodge solid particles tending to dwell thereon.

References Cited UNITED STATES PATENTS 2,265,936 12/1941 Cowles 259-96 2,272,573 2/ 1942 Messmore 259-96 2,641,971 6/1953 Ellis 241-74 2,852,200 9/1958 Holzer 241-46 2,956,753 10/1960 Williamson 241-98 X 3,009,656 11/1961 Martindale 241-46 3,028,634 4/1962 Coghill 241-296 X FRANK T. YOST, Primary Examiner U.S. Cl. X.R.

24l-l9l, 195, 296, 259-96

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